The present invention relates 3-oxa-8-azaprostaglandin analogues useful as potent ocular hypotensives that are particularly suited for the management of glaucoma.
Ocular hypotensive agents are useful in the treatment of a number of various ocular hypertensive conditions, such as post-surgical and post-laser trabeculectomy ocular hypertensive episodes, glaucoma, and as presurgical adjuncts.
Glaucoma is a disease of the eye characterized by increased intraocular pressure. On the basis of its etiology, glaucoma has been classified as primary or secondary. For example, primary glaucoma in adults (congenital glaucoma) may be either open-angle or acute or chronic angle-closure. Secondary glaucoma results from pre-existing ocular diseases such as uveitis, intraocular tumor or an enlarged cataract.
The underlying causes of primary glaucoma are not yet known. The increased intraocular tension is due to the obstruction of aqueous humor outflow. In chronic open-angle glaucoma, the anterior chamber and its anatomic structures appear normal, but drainage of the aqueous humor is impeded. In acute or chronic angle-closure glaucoma, the anterior chamber is shallow, the filtration angle is narrowed, and the iris may obstruct the trabecular meshwork at the entrance of the canal of Schlemm. Dilation of the pupil may push the root of the iris forward against the angle, and may produce pupilary block and thus precipitate an acute attack. Eyes with narrow anterior chamber angles are predisposed to acute angle-closure glaucoma attacks of various degrees of severity.
Secondary glaucoma is caused by any interference with the flow of aqueous humor from the posterior chamber into the anterior chamber and subsequently, into the canal of Schlemm. Inflammatory disease of the anterior segment may prevent aqueous escape by causing complete posterior synechia in iris bombe, and may plug the drainage channel with exudates. Other common causes are intraocular tumors, enlarged cataracts, central retinal vein occlusion, trauma to the eye, operative procedures and intraocular hemorrhage.
Considering all types together, glaucoma occurs in about 2% of all persons over the age of 40 and may be asymptotic for years before progressing to rapid loss of vision. In cases where surgery is not indicated, topical b-adrenoreceptor antagonists have traditionally been the drugs of choice for treating glaucoma.
Certain eicosanoids and their derivatives have been reported to possess ocular hypotensive activity, and have been recommended for use in glaucoma management. Eicosanoids and derivatives include numerous biologically important compounds such as prostaglandins and their derivatives. Prostaglandins can be described as derivatives of prostanoic acid which have the following structural formula: 
Various types of prostaglandins are known, depending on the structure and substituents carried on the alicyclic ring of the prostanoic acid skeleton. Further classification is based on the number of unsaturated bonds in the side chain indicated by numerical subscripts after the generic type of prostaglandin [e.g. prostaglandin E1 (PGE1), prostaglandin E2 (PGE2)], and on the configuration of the substituents on the alicyclic ring indicated by xcex1 or xcex2 [e.g. prostaglandin F2xcex1 (PGF2xcex2)].
Prostaglandins were earlier regarded as potent ocular hypertensives, however, evidence accumulated in the last decade shows that some prostaglandins are highly effective ocular hypotensive agents, and are ideally suited for the long-term medical management of glaucoma (see, for example, Bito, L. Z. Biological Protection with Prostaglandins, Cohen, M. M., ed., Boca Raton, Fla., CRC Press Inc., 1985, pp. 231-252; and Bito, L. Z., Applied Pharmacology in the Medical Treatment of Glaucomas Drance, S. M. and Neufeld, A. H. eds., New York, Grune and Stratton, 1984, pp. 477-505. Such prostaglandins include PGF2xcex1, PGF1xcex1, PGE2, and certain lipid-soluble esters, such as C1 to C2 alkyl esters, e.g. 1-isopropyl ester, of such compounds.
Although the precise mechanism is not yet known experimental results indicate that the prostaglandin-induced reduction in intraocular pressure results from increased uveoscleral outflow [Nilsson et.al., Invest. Ophthalmol. Vis. Sci. (suppl), 284 (1987)].
The isopropyl ester of PGF2xcex1 has been shown to have significantly greater hypotensive potency than the parent compound, presumably as a result of its more effective penetration through the cornea In 1987, this compound was described as xe2x80x9cthe most potent ocular hypotensive agent ever reportedxe2x80x9d [see, for example, Bito, L. Z., Arch. Ophthalmol. 105, 1036 (1987), and Siebold et.al., Prodrug 5 3 (1989)].
Whereas prostaglandins appear to be devoid of significant intraocular side effects, ocular surface (conjunctival) hyperemia and foreign-body sensation have been consistently associated with the topical ocular use of such compounds, in particular PGF2xcex1 and its prodrugs, e.g., its 1-isopropyl ester, in humans. The clinical potentials of prostaglandins in the management of conditions associated with increased ocular pressure, e.g. glaucoma are greatly limited by these side effects.
In a series of co-pending United States patent applications assigned to Allergan, Inc. prostaglandin esters with increased ocular hypotensive activity accompanied with no or substantially reduced side-effects are disclosed. The co-pending U.S. Ser. No. 596,430 (filed 10 Oct. 1990, now U.S. Pat. No. 5,446,041), relates to certain 11-acyl-prostaglandins, such as 11-pivaloyl, 11-acetyl, 11-isobutyryl, 11-valeryl, and 11-isovaleryl PGF2xcex1. Intraocular pressure reducing 15-acyl prostaglandins are disclosed in the co-pending application U.S. Ser. No. 175,476 (filed 29 Dec. 1993). Similarly, 11,15- 9,15 and 9,11-diesters of prostaglandins, for example 11,15-dipivaloyl PGF2xcex1 are known to have ocular hypotensive activity. See the co-pending patent applications U.S. Ser. No. 385,645 (filed 07 Jul. 1989, now U.S. Pat. No. 4,994,274), U.S. Ser. No. 584,370 (filed 18 Sep. 1990, now U.S. Pat. No. 5,028,624) and U.S. Ser. No. 585,284 (filed 18 Sep. 1990, now U.S. Pat. No. 5,034,413). The disclosures of all of these patent applications are hereby expressly incorporated by reference.
8-Azaprostaglandin analogs are disclosed in PCT Patent Application WO 01/46140 A1, WO 02/042268A2, WO 02/24647 A1, WO 03/00794 A1, EP 1 121 939 A2 and Japanese Patent 2001-233792
The present invention concerns a method of treating ocular hypertension which comprises administering to a mammal having ocular hypertension a therapeutically effective amount of a compound of formula I 
wherein hatched lines represent the xcex1 configuration, a triangle represents the xcex2 configuration, a wavy line represents either the xcex1 configuration or the xcex2 configuration and a dotted line represents the presence or absence of a double bond;
D represents a covalent bond or CH2, O, S or NH;
X is CO2R, CONR2, CH2OR, P(O)(OR)2, CONRSO2R, SONR2 or 
Z is CH2 or a covalent bond;
R is H or R2;
R1 is H, R2, phenyl, or COR2;
R2 is C1-C5 lower alkyl or alkenyl and R3 is selected from the group consisting of R2, phenyl, thienyl, furanyl, pyridyl, benzothienyl, benzofuranyl, naphthyl, or substituted derivatives thereof, wherein the substituents maybe selected from the group consisting of C1-C5 alkyl, halogen, CF3, CN, NO2, NR2, CO2R and OR.
In a still further aspect, the present invention relates to a pharmaceutical product, comprising
a container adapted to dispense its contents in a metered form; and
an ophthalmic solution therein, as hereinabove defined.
Finally, certain of the compounds represented by the above formula, disclosed below and utilized in the method of the present invention are novel and unobvious.
The present invention relates to the use of 8-Azaprostaglandin analogs as ocular hypotensives. The compounds used in accordance with the present invention are encompassed by the following structural formula I: 
The preferred group of the compounds of the present invention includes compounds that have the following structural formula II. 
In the above formulae, the substituents and symbols are as hereinabove defined.
In the above formulae:
Preferably D represents a covalent bond or is CH2; more preferably D is CH2.
Preferably Z represents a covalent bond.
Preferably R is H or C1-C5 lower alkyl.
Preferably R1 is H.
Preferably R3 is selected from the group consisting of phenyl and monosubstituted derivatives thereof, e.g. chloro and trifluoromethyl phenyl, i.e. m-chlorophenyl.
Preferably X is CO2R and more preferably R is selected from the group consisting of H and methyl.
The above compounds of the present invention may be prepared by methods that are known in the art or according to the working examples below. The compounds, below, are especially preferred representative, of the compounds of the present invention.
(4-{(R)-2-[(E)-4-(3-chlorophenyl)-3-oxo-but-1-enyl]-5-oxo-pyrrolidin-1-yl}-butoxy)-acetic acid methyl ester
(4-{(R)-2-[(E)-4-(3-Chlorophenyl)-3-oxo-but-1-enyl]-5-oxo-pyrrolidin-1-yl}-butoxy)-acetic acid
(4-{(R)-2-[4-(3-Chlorophenyl)-3-oxo-butyl]-5-oxo-pyrrolidin-1-yl}-butoxy)-acetic acid methyl ester
(4-{(R)-2-[4-(3-Chlorophenyl)-3-oxo-butyl]-5-oxo-pyrrolidin-1-yl}-butoxy)-acetic acid
(4-{(R)-2-[4-(3-Chlorophenyl)-3-hydroxy-butyl]-5-oxo-pyrrolidin-1-yl}-butoxy)-acetic acid methyl ester
(4-{(R)-2-[4-(3-Chlorophenyl)-3-hydroxy-butyl]-5-oxo-pyrrolidin-1-yl}-butoxy)-acetic acid
(4-{(R)-2-[(E)-4-(3-Chlorophenyl)-3-hydroxy-but-1-enyl]-5-oxo-pyrrolidin-1-yl}-butoxy)-acetic acid methyl ester
(4-{(R)-2-[(E)-4-(3-Chlorophenyl)-3-hydroxy-but-1-enyl]-5-oxo-pyrrolidin-1-yl}-butoxy)-acetic acid
Pharmaceutical compositions may be prepared by combining a therapeutically effective amount of at least one compound according to the present invention, or a pharmaceutically acceptable acid addition salt thereof, as an active ingredient, with conventional ophthalmically acceptable pharmaceutical excipients, and by preparation of unit dosage forms suitable for topical ocular use. The therapeutically efficient amount typically is between about 0.0001 and about 5% (w/v), preferably about 0.001 to about 1.0% (w/v) in liquid formulations.
For ophthalmic application, preferably solutions are prepared using a physiological saline solution as a major vehicle. The pH of such ophthalmic solutions should preferably be maintained between 6.5 and 7.2 with an appropriate buffer system. The formulations may also contain conventional, pharmaceutically acceptable preservatives, stabilizers and surfactants.
Preferred preservatives that may be used in the pharmaceutical compositions of the present invention include, but are not limited to, benzalkonium chloride, chlorobutanol, thimerosal, phenylmercuric acetate and phenylmercuric nitrate. A preferred surfactant is, for example, Tween 80. Likewise, various preferred vehicles may be used in the ophthalmic preparations of the present invention. These vehicles include, but are not limited to, polyvinyl alcohol, povidone, hydroxypropyl methyl cellulose, poloxamers, carboxymethyl cellulose, hydroxyethyl cellulose and purified water.
Tonicity adjustors may be added as needed or convenient. They include, but are not limited to, salts, particularly sodium chloride, potassium chloride, mannitol and glycerin, or any other suitable ophthalmically acceptable tonicity adjustor.
Various buffers and means for adjusting pH may be used so long as the resulting preparation is ophthalmically acceptable. Accordingly, buffers include acetate buffers, citrate buffers, phosphate buffers and borate buffers. Acids or bases may be used to adjust the pH of these formulations as needed.
In a similar vein, an ophthalmically acceptable antioxidant for use in the present invention includes, but is not limited to, sodium metabisulfite, sodium thiosulfate, acetylcysteine, butylated hydroxyanisole and butylated hydroxytoluene.
Other excipient components which may be included in the ophthalmic preparations are chelating agents. The preferred chelating agent is edentate disodium, although other chelating agents may also be used in place or in conjunction with it.
The ingredients are usually used in the following amounts:
The actual dose of the active compounds of the present invention depends on the specific compound, and on the condition to be treated; the selection of the appropriate dose is well within the knowledge of the skilled artisan.
The ophthalmic formulations of the present invention are conveniently packaged in forms suitable for metered application, such as in containers equipped with a dropper, to facilitate the application to the eye. Containers suitable for dropwise application are usually made of suitable inert, non-toxic plastic material, and generally contain between about 0.5 and about 15 ml solution.
This invention is further illustrated by the following non-limiting Examples.